1. Field of the Invention
The present invention relates to an electrode pattern for wire bonding to an electrode of a semiconductor device, a substrate, or the like and to a wire bonding method.
2. Background Art
For wire-bonding metal wires to electrodes, it is necessary to teach a bonding position to a bonding apparatus. When wire bonding is performed by using an Au ball, for example, usually a design is made so that each Au ball is within a wire-bonding electrode with sufficient margins. A technique for allowing a wire bonding apparatus to recognize a bonding position in a wire bonding process of manufacture of a semiconductor device is disclosed in JP-A-2001-326241.
A wire-bonding electrode pattern of a laser diode has a long and narrow shape. In recording laser diodes, whereas the optical output that is required for laser diodes increases as the recording speed increases, there is strong demand for price reduction. Some attempts have being made to meet these requirements. To attain a high output power, laser diodes are elongated in the longitudinal direction. To attain price reduction, laser diodes are shortened in the lateral direction so that the number of chips taken from one wafer is increased. For example, in high-output-power (350-mW-class) recording laser diode has very long and narrow shape which is more than 2,000 μm in the longitudinal direction and less than 150 μm in the lateral direction.
A high-output-power recording laser diode is mounted in a package in the following manner. A submount and a laser diode are bonded to an eyelet with AuSn solder or the like. The electrode of the laser diode is wire-bonded to a lead or the eyelet. To form an Au ball at a prescribed position on the electrode, a characteristic pattern of an electrode end portion is recognized and an Au ball is then bonded to the electrode at a position that is shifted from the characteristic pattern by a prescribed length. It is known that when the submount and the laser diode are bonded to the eyelet, the center line of the laser diode can be inclined from that of the eyelet by about 2° at the maximum due to the accuracy of an assembling apparatus.